Containers made of a resin, as represented by bottles made of oriented polypropylene (OPP) and bottles made of polyethylene terephthalate (PET) (PET bottles), are used in various usages, such as for beverages, for food, and for cosmetics. Such containers are generally formed into a predetermined shape by heating a preform made of the resin formed into a bottomed cylindrical shape by injection molding or the like, to a temperature where a stretching effect can be expressed and, in this state, using a blow molding apparatus to perform biaxial stretch blow molding.
As the blow molding apparatus, one is known that uses a pressurized liquid instead of pressurized air as a pressurized fluid to be supplied into the preform. In this situation, by using as the liquid for pressurization a content liquid, such as a beverage, a cosmetic, or a drug that is to be ultimately filled in the container, a process of filling the container with the content liquid can be omitted to simplify a production process thereof and a configuration of the blow molding apparatus.
For example, JP 2014-128911 A describes a blow molding apparatus having: a mold for blow molding to which a preform heated to a stretchable temperature is mounted; a blow nozzle that mates with an open tube portion of the preform mounted to the mold; a filling head that extends along an axial direction of the blow nozzle and is provided at one end with a liquid supply channel connected to the blow nozzle and a liquid introduction channel that extends orthogonally to this liquid supply channel and is connected to this liquid supply channel; and a pressurized liquid supply unit, such as a servo plunger, that is connected to the liquid introduction channel and supplies a pressurized liquid to this liquid introduction channel; wherein the preform is molded into a bottle of a shape conforming to a cavity of the mold by supplying the liquid supplied from the pressurized liquid supply unit into the preform via the blow nozzle and stretching the preform in a horizontal direction (radial direction) while stretching the preform in a vertical direction (axial direction) by a stretching rod.